Geographical variation in AdhF and alcoholic resource utilization in Indian populations of Drosophila melanogaster

Indian geographical populations of Drosophila melanogaster, collected at latitude 10–32.3 ^oN, longitude 76.1–80.1 ^oE and altitude 16–2050 m, were analysed for changes in Adh ¹ frequency and utilization potential of diverse alcoholic resources. Until now, there have been limited data on climatic association of correlated changes on these aspects in continental populations of D. melanogaster. Indian populations demonstrate an increase in Adh ^F frequency by 0.04 per degree latitude and significantly higher utilization of ethanol (9.0–15.2%), acetic acid (8.1–12.5%), n-propanol (2.55-4.25%), 2-propanol (1.5-3.5%), n-butanol (2.15 3.5%) and 2-butanol (0.68-1.2%). Data also revealed significant correlation with latitude as well as altitude. Regression analysis of climatic data from collection sites confirmed the observed clinal variation of Adh ^F as well as alcoholic utilization in D. melanogaster. On the Indian subcontinent, variation in Adh ^F frequency and alcoholic resource utilization along increasing latitude as well as altitude are due to climatic selection factors such as temperature and rainfall.     

A new RNA polymerase sigma factor, σF is required for the late stages of morphological differentiation in Streptomyces spp.

A gene ( sigF ) encoding a new sigma factor was isolated from Streptomyces aureofaciens using a degenerate oligonucleotide probe designed from the GLI(KDNE)A motif lying within the well-conserved region 2.2 of the eubacterial σ⁷⁰ family. Homologues were present in other Streptomyces spp., and that of the genetically well-studied Streptomyces coelicolor A3(2) was also cloned. The nucleotide sequences of the two sigF genes were determined and shown to encode primary translation products of 287 ( S. coelicolor ) and 295 ( S. aureofaciens ) amino acid residues, both showing greatest similarity to σ^B of Bacillus subtilis . However, while σ^B is involved in stationary-phase gene expression and in the general stress response in B. subtilis , σ^F affects morphological differentiation in Streptomyces , Disruption of sigF did not affect vegetative growth but did cause a whi mutant phenotype. Microscopic examination showed that the sigF mutant produced spores that were smaller and deformed compared with those of the wild type, that the spore walls were thinner and sensitive to detergents and that in sigF mutant spores the chromosome failed to condense. σ^F is proposed to control the late stages of spore development in Streptomyces .     

Ca2+ dependence and La3+ interference of ultraviolet radiationinduced K+ efflux from rose cells

A low fluence of ultraviolet radiation (UV) causes cultured cells of Rosa damascena Mill cv. Gloire de Guilan to lose intracellular K⁺. This effect required the presence of Ca²⁺ in the medium. A reduction in the concentration of free Ca²⁺ to 10⁻⁵ M with ethyleneglycol-bis-(β-aminoethyl-ether)-N.N.N',N'-tetraacetic acid (EGTA) buffer inhibited the UV-stimulated efflux; this was correlated with a discharge of the membrane potential and a stimulation of the leakage of K⁺ from unirradiated cells. All the same effects were seen with La³⁺ at 0.2 m M. At 0.02 m M La³⁺, the UV-stimulated efflux of K⁺ was blocked without concomitant effects on the membrane potential or K⁺ efflux from control cells. It is suggested that removal of Ca²⁺ blocks or masks the UV-induced leakage of K⁺ by destabilizing the plasma membrane. In addition, La³⁺ may specifically inhibit the UV-stimulated opening of K⁺ or anion channels.     

An SNP in the goat CSN2 promoter region is associated with the absence of beta-casein in milk

So far, at least eight alleles in the goat CSN2 locus have been associated with the level of β -casein expression in milk. Alleles CSN2 ^A , CSN2 ^{A 1}, CSN2 ^B , CSN2 ^C , CSN2 ^D and CSN2 ^E have been associated with normal content (allele effects of about 5 g of β -casein per litre), whereas the CSN2 ⁰ and CSN2 ⁰¹ alleles have been associated with non-detectable levels of β -casein. Most of these alleles have been characterized genetically. Herein, we report the identification of a previously unreported SNP in the goat CSN2 promoter region ( AJ011018 :g.1311T>C), which is associated with the absence of β -casein in the milk. Furthermore, we developed a PCR-based method that allows detection of this mutation.     

Kinetics, Pharmacology, and Autoradiographic Distribution of l-[3H]Nitroarginine Binding Sites in Rat Cerebellum

Abstract: The kinetics and pharmacology of N ^G-nitro- l -[2,3,4,5-³H]arginine ( l -[³H]NOARG) binding to rat cerebellum were investigated using in vitro radioligand binding. Specific l -[³H]NOARG binding in cerebellum was of nanomolar affinity, reversible, saturable, and best fit to a single-site model. Specific binding was Ca²⁺ dependent and sensitive to pH (with an optimum of 5.5–7.0). Added calmodulin (1.5–40 µg/ml) had no influence on specific l -[³H]NOARG binding. However, the calmodulin antagonists W-5, W-13, and calmidazolium inhibited l -[³H]NOARG binding with IC₅₀ values in the micromolar range, and calmodulin (10 µg/ml) competitively reversed this inhibition. Nitric oxide synthase (NOS) inhibitors ( N ^G-nitro- l -arginine methyl ester and N ^G-monomethyl- l -arginine acetate) and l -arginine displaced l -[³H]NOARG binding with IC₅₀ values in the nanomolar range, whereas d -arginine and basic amino acids ( l -lysine and l -histidine) displaced l -[³H]NOARG binding with IC₅₀ values in the millimolar range. A comparison of the NOS functional assay with l -[³H]NOARG binding in rat cerebellum showed similar profiles of Ca²⁺ dependency and inhibitory kinetics. Quantitative autoradiographic distribution of l -[³H]NOARG binding sites was significantly higher in the molecular layer than in the granular layer of cerebellum. These studies confirm the potential use of l -[³H]NOARG binding to study the regional distribution and functional properties of NOS.     

A comparison of NH4+ and NO3– net fluxes along roots of rice and maize

Net fluxes of NH₄⁺ and NO₃^– along adventitious roots of rice ( Oryza sativa L.) and the primary seminal root of maize ( Zea mays L.) were investigated under nonperturbing conditions using ion-selective microelectrodes. The roots of rice contained a layer of sclerenchymatous fibres on the external side of the cortex, whereas this structure was absent in maize. Net uptake of NH₄⁺ was faster than that of NO₃^– at 1 mm behind the apex of both rice and maize roots when these ions were supplied together, each at 0·1 mol m^–3. In rice, NH₄⁺ net uptake declined in the more basal regions, whereas NO₃^– net uptake increased to a maximum at 21 mm behind the apex and then it also declined. Similar patterns of net uptake were observed when NH₄⁺ or NO₃^– was the sole nitrogen source, although the rates of NO₃^– net uptake were faster in the absence of NH₄⁺. In contrast to rice, rates of NH₄⁺ and NO₃^– net uptake in the more basal regions of maize roots were similar to those near the root apex. Hence, the layer of sclerenchymatous fibres may have limited ion absorption in the older regions of rice roots.     

Genetic polymorphism of the sixth component of complement (C6) in dogs

Using agarose gel isoelectric focusing and immunoblotting with rabbit anti-rabbit C6, a genetic polymorphism was found in the sixth component of complement (C6) in 18 Asian native breeds or populations and three European breeds of dog. The C6 locus was highly polymorphic. The phenotype distribution data indicated that dog C6 phenotypes were controlled by seven codominant alleles, C6 ^A, C6 ^B, C6 ^C, C6 ^D, C6 ^E, C6 ^F and C6 ^G, at a single autosomal locus. Breed differences were observed among the gene frequencies, especially between Asian and European breeds. Two gene flows from the adjacent areas into Japanese native dogs were postulated.     

l-[3H]Nitroarginine and l-[3H]Arginine Uptake into Rat Cerebellar Synaptosomes: Kinetics and Pharmacology

Abstract: Characteristics of the transport of the nitric oxide synthase substrate l -arginine and its inhibitor, N ^G-nitro- l -arginine ( l -NOARG), into rat cerebellar synaptosomes were studied. Uptake of both l -arginine and l -NOARG was linear with increasing amount of protein (up to 40 µg) and time of incubation (up to 5 min) at 37°C. Uptake of both compounds reached a steady state by 20 min. Maximal uptake of l -NOARG (650 pmol/mg of protein) was three to four times higher than that of l -arginine (170 pmol/mg of protein). l -NOARG uptake showed biphasic kinetics ( K _{m 1} = 0.72 m M , V _{max 1} = 0.98 nmol/min/mg of protein; K _{m 2} = 2.57 m M , V _{max 2} = 16.25 nmol/min/mg of protein). l -Arginine uptake was monophasic with a K _m of 106 µ M and a V _max of 0.33 nmol/min/mg of protein. l -NOARG uptake was selectively inhibited by l -NOARG, N ^G-nitro- l -arginine methyl ester, and branched-chain and aromatic amino acids. l -Alanine and l -serine also inhibited l -NOARG uptake but with less potency. Uptake of l -arginine was selectively inhibited by N ^G-monomethyl- l -arginine acetate and basic amino acids. These studies suggest that in rat cerebellar synaptosomes, l -NOARG is transported by the neutral amino acid carrier systems T and L with high affinity, whereas l -arginine is transported by the basic amino acid carrier system y⁺ with high affinity. These data indicate that the concentration of competing amino acids is an important factor in determining the rates of uptake of l -NOARG and l -arginine into synaptosomes and, in this way, may control the activity of nitric oxide synthase.     

Expression of a pepT homologue from Bacillus subtilis

Abstract We isolated pepT from Bacillus subtilis , a gene with homology to various tripeptidases from different bacterial sources, pepT is preceded by genes encoding a two component regulatory system. Its expression is activated during stationary phase. In minimal medium this activation is boosted in the presence of phosphate. The response regulator is preceded by putative promoter consensus sequences recognized by the stationary phase specific sigma factors σ ^H, σ ^F, and σ ^G. This is in accordance with the initiation of expression at the beginning of stationary phase. Inactivation of pepT causes no obvious phenotype.     

Impairment of Na+,K+-ATPase activity following enterotoxigenic Campylobacter jejuni infection: changes in Na+, Cl− and 3-O-methyl-D-glucose transport in vitro, in rat ileum

Abstract Unidirectional fluxes of Na⁺, Cl⁻ and 3-O-methyl-D-glucose (3-MG) were measured in vitro across Campylobacter jejuni live culture-infected and control rat ileal short-circuited tissues by the Using Chamber technique. Net secretion of Na⁺ and enhanced secretion of Cl⁻ ions was observed in the infected animals ( P < 0.001, n =6) as compared to the net absorption of Na⁺ and marginal secretion of Cl⁻ ions in the control animals. There was a significant decrease in the mucosal-to-serosal fluxes of 3-MG in C. jejuni -infected rat ileum. The specific Na⁺,K⁺-ATPase activity when measured biochemically in the membrane-rich fraction of enterocytes was found to be significantly lower (58%) in the infected group as compared to the control group ( P < 0.001). Our results therefore suggest that infection with an enterotoxigenic C. jejuni inhibits the Na⁺,K⁺-ATPase activity in rat enterocytes. The impairment of Na⁺,K⁺-ATPase activity thus appears to induce a secondary change in Na⁺,Cl⁻ and 3-MG transport in vitro in rat ileum.     

Induction of nitrate reductase in needles of Scots pine seedlings by NOX and NO3−

The possibility to induce nitrate reductase (NR; EC 1.6.6.2) in needles of Scots pine ( Pinus sylvestris L.) seedlings was studied. The NR activity was measured by an in vivo assay. Although increased NR activities were found in the roots after application of NO₃⁻, no such increase could be detected in the needles. Detached seedlings placed in NO₃⁻ solution showed increasing NR activities with increasing NO₃⁻ concentrations. Exposure of seedlings to NO_x (70–80 ppb NO₂ and 8–12ppb NO) resulted in an increase of the NR activity from 10–20 nmol NO₂⁻ (g fresh weight)⁻¹ h⁻¹ to about 400 nmol NO₂⁻ (g fresh weight)⁻¹ h⁻¹. This level was reached after 2–4 days of exposure, thereafter the NR activity decreased to about 200 nmol NO₂⁻ (g fresh weight)⁻¹ h⁻¹. Analyses of free amino acids showed low concentrations of arginine and glutamine in NO_x-fumigated seedlings compared to corresponding controls.     

Regulation of K+ and NO3− fluxes in roots of sunflower (Helianthus annuus) after changes in light intensity

Shoot activity has been reported to affect rates of ion uptake by plant roots in other ways than merely through supply of assimilates. To elucidate the mechanisms by which a signal from the upper part of the plant controls the rate of K⁺ and NO₃⁻ uptake by roots, both uptake of K⁺ and NO₃⁻ and secretion into the xylem of young sunflower plants ( Helianthus annuus L.) were measured after changes in light intensity.
No close correlation was observed between the uptake of NO₃⁻ and that of K⁺; an increase in light intensity produced a much greater stimulation of NO₃⁻ uptake than of K⁺ uptake. On the other hand, secretion of NO₃⁻ into the xylem was tightly coupled to that of K⁺, and this coupling was strongly disturbed by excision of the root. The results suggest the involvement of the K₂-malate shuttle on the regulation by the shoot of K⁺ and NO₃⁻ secretion in the xylem, which is linked to NO₃⁻ uptake, while K⁺ uptake is independent of this regulation mechanism.     

Effect of darkness and CO2 starvation on NH4+ and NO3− assimilation in the unicellular alga Cyanidium caldarium

Cyanidium caldarium (Tilden) Geitler, a non-vacuolate unicellular alga, resuspended in medium flushed with air enriched with 5% CO₂, assimilated NH₄⁺ at high rates both in the light and in the dark. The assimilation of NO₃⁻, by contrast, was inhibited by 63% in the dark. In cell suspensions flushed with CO₂-free air, NH₄⁺ assimilation decreased with time both in the light and in the dark and ceased almost completely after 90 min. The addition of CO₂ completely restored the capacity of the alga to assimilate NH₄⁺. NO₃⁻ assimilation, by contrast, was 33% higher in the absence of CO₂ and was linear with time. It is suggested that NO₃⁻ and NH₄⁺ metabolism in C. caldarium are differently controlled in response to the light and carbon conditions of the cell.     

Heterogeneous Na+ Sensitivity of Na+,K+-ATPase Isoenzymes in Whole Brain Membranes

Abstract: The Na⁺ sensitivity of whole brain membrane Na⁺,K⁺-ATPase isoenzymes was studied using the differential inhibitory effect of ouabain (α1, low affinity for ouabain; α2, high affinity; and α3, very high affinity). At 100 m M Na⁺, we found that the proportion of isoforms with low, high, and very high ouabain affinity was 21, 38, and 41%, respectively. Using two ouabain concentrations (10⁻⁵ and 10⁻⁷ M ), we were able to discriminate Na⁺ sensitivity of Na⁺, K⁺-ATPase isoenzymes using nonlinear regression. The ouabain low-affinity isoform, α1, exhibited high Na⁺ sensitivity [ K _a of 3.88 ± 0.25 m M Na⁺ and a Hill coefficient ( n ) of 1.98 ± 0.13]; the ouabain high-affinity isoform, α2, had two Na⁺ sensitivities, a high ( K _a of 4.98 ± 0.2 m M Na⁺ and n of 1.34 ± 0.10) and a low ( K _a of 28 ± 0.5 m M Na⁺ and an n of 1.92 ± 0.18) Na⁺ sensitivity activated above a thresh old (22 ± 0.3 m M Na⁺); and the ouabain very-high-affinity isoform, α3, was resolved by two processes and appears to have two Na⁺ sensitivities (apparent K _a values of 3.5 and 20 m M Na⁺). We show that Na⁺ dependence in the absence of ouabain is the result of at least of five Na⁺ reactivities. This molecular functional characteristic of isoenzymes in membranes could explain the diversity of physiological roles attributed to isoenzymes.     

Excretion of ions (Cd2+, Li+, Na+ and Cl−) by Tamarix aphylla

Excretion of minerals by the NaCl-resistant and comparatively cadmium-resistant tree Tamarix aphylla (L.) Karst, was investigated. Cd²⁺ was excreted by plants exposed for 1–10 days to 9 or 45 μ M Cd²⁺ solutions. Excretion of this toxic ion increased considerably with time but was less than 5% of the quantities that had been accumulated in the shoots. Excretion of Na⁺ and Cl⁻ was positively correlated with NaCl concentration (1.5, 10, 50 m M ) of the medium. The Na⁺/Cl⁻ ratios of the excrete were positively correlated with the concentration of the treatment solution. Ca²⁺ excretion decreased with increasing NaCl concentrations of the solution. Excretion of K⁺ and Mg²⁺ was only little affected by NaCl. Excretion of Li⁺ occurred whenever this element was supplied in the uptake solution; daily excretion rates of Li⁺ increased with time. The ecological significance of excretion is discussed in relation to the low selectivity of the mechanism in T. aphylla .     

Passive uptake of K+(86Rb+) in sunflower roots at low external K+ concentrations

Passive fluxes of K⁺ (⁸⁶Rb) into roots of sunflower ( Helianthus annuus L. cv. Uniflorus) were determined at low K⁺ concentration (0.1 and 1.0 mM K⁺) in the ambient solution. Metabolic uptake of K⁺ was inhibited by 10⁻⁴M 2,4-dinitrophenol (DNP). K⁺ (⁸⁶Rb) fluxes were studied both continuously and by time differentiation of uptake. In high K⁺ roots passive uptake was directly proportional to the K⁺ concentration of the uptake solution, indicating free diffusion. This assumption was supported by the fact that passive Rb⁺ uptake was not affected by high K⁺ concentrations. In low K⁺ roots the passive uptake of K⁺ was higher than in high K⁺ roots. The increase was possibly due to carrier-mediated K⁺ transport. As K⁺ effluxes were quantitatively similar to influxes, it is suggested that passive K⁺ fluxes represent exchange diffusion without relation to net K⁺ transport.     

The immune response against Francisella tularensis live vaccine strain in Lpsn and Lpsd mice

Abstract The impact of Lps gene on the course of immune response against subcutaneous infection of mice with Francisella tularensis live vaccine strain was studied. Production and specificity of antibodies, cytotoxic responses of macrophages and NK-cells, spontaneous production ex vivo of cytokines IL-1α, IL-2, IL-4, IL-6, IL-10, IFN-γ, and TNF-α in spleen cell cultures in C3H/HeJ ( Lps ^d) mice in comparison with C3H/HeN ( Lps ^r) mice were tested. The value of LD₅₀ was significantly different in the two strains of mice (8.0 × 10³ cfu for C3H/HeJ versus 4.61 × 10⁵ cfu for C3H/HeN mice after subcutaneous inoculation). The production of NO₂ is also impaired in C3H/HeJ mice in the early intervals after infection. Thus, the defective Lps gene of C3H/HeJ mice influences both the level of innate resistance of mice to F. tularensis live vaccine strain infection and the process of induction and regulation of immune response against this intracellular bacterial pathogen.